I think GRRM is failing the first two obligations of the author: https://medium.com/luminasticity/obligations-of-the-author-0...

Finish what you start — When starting a work that has readers or viewers, complete it if it is financially rewarding to do so. You have unfortunately made an aesthetic promise to your readers in exchange for money. Suck it up.

Keep Your Customers Informed — If you will not be able to do the first, inform people as soon as possible.

I'm with Gaiman on this. No author has any obligation, ethical or otherwise, to provide further books in a series to the readers unless those readers are paying hard cash upfront for the missing books.

And what on earth is is an 'aesthetic promise'?